Total traffic volume on optical networks which are in service has over a period of time increased. Additionally, the percent of data traffic versus voice traffic on such networks is continually increasing.
Responsive to ongoing needs for servicing the increasing both data and voice traffic an expanded network architecture has been defined in ITU standard G.872 entitled “Architecture of Optical Transport Networks (OTN)”. ITU standard G.709 entitled “Interfaces for Optical Transport Networks” defines an implementation of an optical channel by means of digital framed signals. G.709 provides for the use of forward error correction which is intended to reduce transmission errors on noisy links. This capability in turn facilitates the deployment of longer optical spans. Both ITU G.872 and G.709 are incorporated herein by reference.
The G.709 standard provides for forward error correction using Reed-Salomon RS code. Using such codes, multiple transmission errors can be corrected at the receiving end. G.709 supports only a single FEC mode.
The ongoing development of products which implement the G.709 standard has resulted in a situation where a variety of forward error correction modes need to be supported. These include:
1. Standard FEC mode as defined in ITU G.709;
2. Enhanced vendor-developed FEC modes; and
3. No FEC mode.
There thus is an ongoing need to be able to communicate the FEC mode being used between the respective transmitter/receiver. Preferably, such communication could be implemented without imposing additional overhead on the transmissions while at the same time providing flexibility such that different FEC operational modes can be readily supported between transmitter and receiver, new as yet undefined modes can be incorporated as subsequently developed and multi-mode transmitters and receivers can be readily combined with singular mode receivers and transmitters.